[PATCH v10 5/8] drm/xe/eustall: Add support to handle dropped EU stall data

[Dixit, Ashutosh]

On Tue, 18 Feb 2025 11:53:55 -0800, Harish Chegondi wrote:
>
> If the user space doesn't read the EU stall data fast enough,
> it is possible that the EU stall data buffer can get filled,
> and if the hardware wants to write more data, it simply drops
> data due to unavailable buffer space. In that case, hardware
> sets a bit in a register. If the driver detects data drop,
> the driver read() returns -EIO error to let the user space
> know that HW has dropped data. The -EIO error is returned
> even if there is EU stall data in the buffer. A subsequent
> read by the user space returns the remaining EU stall data.
>
> v10: Reverted the changes back to v8:
>      Clear the drop bits only after reading the data.

I think I am ok with this patch as is. Unless we agree to drop data in the
driver (which I had proposed but you had rejected), I don't think we can do
a lot more without really complicating things. So I don't want to go there
yet.

But lets first go through the coments on PATCH v10 4/8. Once we resolve the
locking issue raised there, I will review this patch again and hopefully
R-b it.

See if you need to send a new revision of the series.

Thanks.
--
Ashutosh